JP2895282B2 - Thermal transfer recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording apparatus for recording an image having an intermediate gradation density, such as a video printer and a thermal printer.

[0002]

2. Description of the Related Art In a thermal transfer recording apparatus for recording an image having an intermediate gradation density using a thermal head having a plurality of heating elements, the resistance value of each heating element is determined when the voltage applied to the thermal head is constant. The amount of heat changes due to the variation in the recording density, and when a uniform pattern with a constant gradation is recorded, the recording density becomes uneven.

As a thermal transfer recording apparatus capable of correcting the unevenness of the recording density due to the variation of the resistance value, for example,
There is one described in JP-A-1-216860. In this already-proposed example, in a state where correction is not performed in advance, a uniform pattern with a fixed gradation at a specific gradation is recorded, and the recording density at each heating element is measured with a microdensitometer from the recording result. From the measurement result, a correction amount is obtained for each heating element based on the heat generation amount of each heating element. Then, the obtained correction amount is written into a read-only memory (hereinafter, referred to as ROM), and at the time of recording, the gradation of the image data is converted based on the correction amount for each heating element to obtain a resistance. The non-uniformity (unevenness) of the recording density due to the variation of the values is corrected.

[0004]

In the above-mentioned prior art, the recording result of recording a uniform pattern at a certain specific gray scale is calculated as follows.
The recording density of each heating element is measured, and a correction amount is obtained for each heating element from the measurement result.When recording, the same correction is applied over the entire recording density range based on the correction amount. I was doing.

However, originally, the optimum correction amount differs depending on the gradation, and as described above, based on the correction amount obtained from the result of recording a uniform pattern at a certain specific gradation, all the recording density ranges are determined. If the same correction is performed over a period of time, there is a problem that the correction may be excessive or insufficient depending on the recording density.

[0006] Also, if such a correction has been made,
When the color of the ink paper is changed, a basic gamma characteristic (yellow,
A gamma characteristic (gradation vs. density characteristic) assuming that gray ink paper obtained by mixing magenta and cyan colors is used, and is hereinafter referred to as a basic gamma characteristic. ), Or when the combination of ink paper and photographic paper (hereinafter referred to as the medium) is changed, the excess or deficiency of correction similarly occurs even if all other conditions are the same. was there.

An object of the present invention is to solve such a problem,
In addition to correcting the non-uniformity (unevenness) of the recording density due to the variation of the resistance value of each heating element in the thermal head, it can be used to change the recording density, change the color of the ink paper, change the basic gamma characteristic, and change the media. On the other hand, an object of the present invention is to provide a thermal transfer recording apparatus capable of always performing uniform and good recording without causing excessive or insufficient correction.

[0008]

In order to achieve the above object, according to the present invention, a resistance value of a heating element of a thermal head is measured by measuring the resistance value of each heating element one element at a time and a basic gamma characteristic. A correction data storage unit for storing correction data set in advance corresponding to each gradation for each heating element, an image data, and a correction data storage unit.
Image data synthesizing means for synthesizing the correction data read out corresponding to the gradation number of the image data for each element, and outputting the synthesized data as corrected image data, and performing recording based on the corrected image data. I made it.

Further, there is provided a gamma characteristic selecting means for selecting and setting a desired basic gamma characteristic from a plurality of basic gamma characteristics, and the image data is read out from the image data and the correction data storage means by the image data synthesizing means. Combined with the correction data for the set basic gamma characteristic,
The corrected image data is used.

Further, a media discriminating means for discriminating a medium is provided, and the image data synthesizing means synthesizes the image data and the correction data for the discriminated media read from the correction data storage means, The corrected image data is used.

Further, a resistance value measuring means for measuring the resistance value of the heating element of the thermal head one element at a time before recording is provided, and correction data is calculated from the measured resistance value data according to the gamma characteristic or the medium. The image data is combined with the image data to obtain corrected image data.

[0012]

Therefore, according to the present invention, correction data set in advance based on the resistance value of each heating element of the thermal head and the basic gamma characteristic set in the apparatus is synthesized with image data. Since the correction image data is optimized for each heating element and recording is performed based on the corrected image data, the non-uniformity (unevenness) of the recording density due to the variation in the resistance value of each heating element is corrected, and the uniformity is obtained regardless of the density. Good recording results are obtained.

[0013] Even when a plurality of basic gamma characteristics or a plurality of media are present, the optimum correction data is set in advance for each of the set basic gamma characteristics or the determined media based on the resistance value. With respect to the set basic gamma characteristic or the determined medium, a uniform and good recording result is always obtained regardless of the density.

Further, by measuring the resistance value of each heating element of the thermal head before recording, even if the resistance value of the heating element changes, optimal correction data is set. The non-uniformity (unevenness) of the recording density due to the variation in the values can be corrected.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a thermal transfer recording apparatus as a first embodiment of the present invention, wherein 1 is an image source, 2 is an image memory, 3 is a halftone control unit, 401 is a system controller, and 501 is a correction. ROM, 6 is an image data synthesizing unit, 7
Reference numeral 01 denotes an energization data storage unit, 9 denotes a thermal head, 10 denotes ink paper, 11 denotes recording paper, and 12 denotes a drum.

First, the recording operation will be described. Image data taken in from the image source 1 before recording is written in the image memory 2. When a recording command is issued, the system controller 401 sends a signal indicating the number of each heating element of the thermal head 9 and a signal indicating the first color of the ink paper 10 to the image memory 2 and the correction ROM 501.

Further, the system controller 401 receives the energization time data of the first color corresponding to the gradation number from the energization data storage unit 701 and sends the data to the halftone control unit 3. If only the energizing time data for the discrete gray scale numbers can be received from the energizing data storage unit 701, the system controller 401 calculates the energizing time data for the other gray scale numbers by a complementary operation, and After obtaining the energization time data for the key number, send it.

The image memory 2 sends a signal indicating the gradation number of the image data of the first color to the correction ROM 501 in accordance with the number of each heating element of the thermal head 9 which has been sent, and the image data of the first color. To the image data synthesizing unit 6.
Further, the correction ROM 501 sends correction data of the first color to the image data synthesizing unit 6 in accordance with the number of each heating element of the thermal head 9 and the gradation number of the image data.

In the image data synthesizing section 6, the transmitted 1
The color image data and the correction data are combined into corrected image data, and then sent to the halftone control unit 3. In the halftone control unit 3, when the corrected image data for one line is prepared,
The energization time data sent from the system controller 401 is received, and a strobe signal having a time width corresponding to the energization time data is sent to the thermal head 9. The thermal head 9 supplies a current to each heating element for the time width of the transmitted strobe signal, and each heating element generates heat in response to the current.

On the other hand, the recording paper 11
Is wound, and the first color ink paper 10 is laid thereon, and is pressed by the thermal head 9. The amount of heat generated by the heating element changes according to the energization time (that is, the time width of the strobe signal) specified by the halftone control unit 3,
The ink according to the calorific value is transferred from the ink paper 10 to the recording paper 1.
1 and halftone recording is performed. Similarly, printing is performed in the second and subsequent lines and in the second and subsequent colors according to the corrected image data corrected for each heating element.

Next, the correction data in the correction ROM 501 will be described. FIG. 2 is a characteristic diagram showing an example of a gamma characteristic for each ink color of the ink paper 10.

In this embodiment, three colors are used: yellow (hereinafter, referred to as Ye) indicated by a solid line, magenta (hereinafter, referred to as Mg) indicated by a dotted line, and cyan (hereinafter, referred to as Cy) indicated by a dashed line. The case will be described.

In general, in a thermal transfer recording apparatus, when realizing a desired good recording (ie, when realizing a certain basic gamma characteristic), as shown in FIG. It is necessary to record with different gamma characteristics for each ink color. For this reason, the density change amount with respect to the gradation change amount differs depending on the gradation number and also on the color of the ink.

FIG. 3 is an explanatory diagram showing an example of correction data in a correction ROM 501 for a certain heating element in the thermal head 9. FIG. 3 shows a case where the image data is 8 bits (256 gradations).

For each color of ink on the ink paper 10 (Ye, M
g, Cy) according to the gradation number of the image data.
(PM0, PC0), PY1 (PM1, PC1) ... PY
n (PMn, PCn),... PY255 (PM255, P
C255) is written in correspondence with the heating element.

The correction data is a difference data between the previously measured resistance value of each heating element of the thermal head 9 and the average value, the maximum resistance value, or the minimum resistance value of the resistance values of all the heating elements. Is obtained for each gradation of each ink color based on the gamma characteristic of each ink color of the ink paper 10.

Correction data for the number of heating elements of the thermal head 9 is written in the correction ROM 501. As described above, a signal indicating the number of each heating element is received from the system controller 401, and the correction data corresponding to the number is received. Select data.

Next, generation of corrected image data in the image data synthesizing section 6 will be described. As described above, when the recording command is issued, the system controller 401 sends a signal indicating the number of each heating element of the thermal head 9 and the ink paper 10.
The signal indicating the color of the first color is stored in the image memory 2 and the correction ROM.
Send to 501

In the image memory 2, the gradation number of the first image data of the first line of the first color is corrected by the correction ROM 50.
1 to the image data synthesizing unit 6. The correction ROM 501 reads out the correction data corresponding to the gradation number of the image data sent from the image memory 2 from the correction data area for the first heating element of the first color, and sends it to the image data synthesizing unit 6.

The image data synthesizing unit 6 synthesizes the image data from the image memory 2 and the correction data from the correction ROM 501 to generate corrected image data, and sends the corrected image data to the halftone control unit 3. For example, in FIG. 3, when the gradation number of the Ye image data is 3, the Ye correction data is PY3. In the image data synthesizing unit 6, the image data 3 and the correction data P
Y3 is added, and (3 + PY3) is set as corrected image data.

As described above, according to this embodiment, the ink paper 10 is adjusted in accordance with the gradation of the image data.
The optimal corrected image data can be set and recorded for each heating element of the thermal head 9 in accordance with the gamma characteristic of each color of the ink, so that the resistance value variation of each heating element in the thermal head 9 can be reduced. The resulting non-uniformity (unevenness) of the recording density can be corrected.

FIG. 4 is a block diagram showing a thermal transfer recording apparatus according to a second embodiment of the present invention, wherein 402 is a system controller, 502 is a correction ROM, 702 is an energization data storage, and 20 is a gamma characteristic selection. Department. In addition, the same members as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals.

Hereinafter, the recording operation will be described. Image data taken in from the image source 1 before recording is written in the image memory 2.

When a recording command is issued, the system controller 402 sends a signal indicating the number of each heating element of the thermal head 9 and a signal indicating the first color of the ink paper 10 to the image memory 2 and the correction ROM 502.

The gamma characteristic selection section 20 sends information on the set basic gamma characteristics to the correction ROM 502 and the system controller 402. Note that the gamma characteristic selection unit 20
A gamma characteristic switching switch (not shown) and the like are provided. By switching the switch, a basic gamma characteristic for recording is selected and set.

The system controller 402 also receives, from the energization data storage unit 702, energization time data of the first color corresponding to the gradation number for the set basic gamma characteristic, and sends the data to the halftone control unit 3. Energization data storage 7
02 stores energization time data corresponding to a plurality of types of basic gamma characteristics. The energization data storage 7
If only the energization time data for the discrete gradation numbers can be received from the system controller 40,
No. 2 calculates the energization time data for the other gradation numbers by the complementary operation, obtains the energization time data for all the gradation numbers, and then sends the data.

The image memory 2 sends a signal indicating the gradation number of the image data of the first color to the correction ROM 502 in accordance with the number of each heating element of the thermal head 9 sent thereto, and the image data of the first color. To the image data synthesizing unit 6.
Further, in the correction ROM 502, the correction data of the first color for the set basic gamma characteristic is stored in the image data synthesizing unit 6 in accordance with the number of each heating element of the thermal head 9 and the gradation number of the image data sent thereto. Send to

In the image data synthesizing section 6, the transmitted 1
The color image data and the correction data are combined into corrected image data, and then sent to the halftone control unit 3. In the halftone control unit 3, when the corrected image data for one line is prepared,
The energization time data for the set basic gamma characteristic is received from the system controller 402, and a strobe signal having a time width corresponding to the energization time data is sent to the thermal head 9. The thermal head 9 supplies a current to each heating element for the time width of the transmitted strobe signal, and the heating element generates heat in response to the current.

On the other hand, the recording paper 11
Is wound, and the first color ink paper 10 is laid thereon, and is pressed by the thermal head 9. The amount of heat generated by the heating element changes according to the energization time (that is, the time width of the strobe signal) specified by the halftone control unit 3,
The ink according to the calorific value is transferred from the ink paper 10 to the recording paper 1.
1 and halftone recording is performed. Similarly, printing is performed in the second and subsequent lines and in the second and subsequent colors according to the corrected image data corrected for each heating element.

Next, the correction data in the correction ROM 502 will be described. FIG. 5 is a characteristic diagram showing an example of the basic gamma characteristic set in the present apparatus. In the present embodiment, a case will be described in which there are three basic gamma characteristics A set in the apparatus, a basic gamma characteristic A indicated by a solid line, a basic gamma characteristic B indicated by a dotted line, and a basic gamma characteristic C indicated by a dashed line.

As described with reference to FIG. 2, in order to realize a certain set basic gamma characteristic, it is necessary to perform recording with a different gamma characteristic for each ink color of the ink paper 10. Also, if the set basic gamma characteristics are different, the gamma characteristics will be different even if the ink color is the same. Therefore, the density change amount with respect to the gradation change amount differs depending on the gradation number, the color of the ink on the ink paper 10, and further depending on the basic gamma characteristic.

FIG. 6 is an explanatory diagram showing an example of correction data in the correction ROM 502 for a certain heating element in the thermal head 9. FIG. 6 shows a case where the image data is 8 bits (256 gradations).

In the basic gamma characteristic A, PY0-L (PM0-L, PC0-L), PY0-L (PM0-L, PC0-L) according to the gradation number of the image data for each color (Ye, Mg, Cy) of the ink on the ink paper 10.
PY1-L (PM1-L, PC1-L) ... PYn-L
(PMn-L, PCn-L),... PY255-L (PM
The correction data 255-L and PC255-L) are written in correspondence with the number of heating elements.

Similarly, in the basic gamma characteristic B, PY0−
V (PM0-V, PC0-V), PY1-V (PM1-
V, PC1-V) PYn-V (PMn-V, PCn-
V),... PY255-V (PM255-V, PC255
Correction data of -V) is written for the number of heating elements corresponding to the heating elements.

Similarly, in the basic gamma characteristic C, PY0−
M (PM0-M, PC0-M), PY1-M (PM1-
M, PC1-M) ... PYn-M (PMn-M, PCn-
M), PY255-M (PM255-M, PC255
Correction data of −M) is written for the number of heating elements corresponding to the heating elements.

The correction data is a difference data between the previously measured resistance value of each heating element of the thermal head 9 and the average value, the maximum resistance value, or the minimum resistance value of the resistance values of all the heating elements. Is calculated for each gradation based on the set basic gamma characteristic and the set ink color based on the gamma characteristics for each color of the ink of the ink paper 10 in each of the plurality of types of basic gamma characteristics set in the apparatus. I have.

Next, generation of corrected image data in the image data synthesizing section 6 will be described. As described above, when the recording command is issued, the system controller 402 sends a signal indicating the number of each heating element of the thermal head 9 and the ink paper 10.
The signal indicating the color of the first color is stored in the image memory 2 and the correction ROM
Send to 502.

In the image memory 2, the gradation number of the first image data of the first line of the first color is corrected by the correction ROM 50.
2 to the image data synthesizing unit 6. The correction ROM 502 reads the correction data corresponding to the gradation number of the image data sent from the image memory 2 from the correction data area for the first heating element of the first color for the set basic gamma characteristic, and reads the image data. It is sent to the synthesis unit 6.

The image data synthesizing section 6 synthesizes the image data from the image memory 2 and the correction data from the correction ROM 502 to obtain corrected image data, and sends it to the halftone control section 3. For example, in FIG. 6, when the tone number of the Ye image data is 3, the Ye correction data for the basic gamma characteristic A is PY3-L. In the image data synthesizing unit 6,
Add 3 of the image data and PY3-L of the correction data,
Let (3 + PY3-L) be the corrected image data.

As described above, according to the present embodiment, the gamma characteristic of each ink color of the ink paper 10 is adjusted in accordance with the gradation of the image data and the set basic gamma characteristic. The image data is corrected, and the optimum corrected image data is set for each heating element of the thermal head 9,
Since recording can be performed, non-uniformity (unevenness) of recording density due to variation in resistance value of each heating element of the thermal head 9 can be corrected.

FIG. 7 is a block diagram showing a thermal transfer recording apparatus according to a third embodiment of the present invention, wherein 403 is a system controller, 503 is a correction ROM, 703 is a power supply data storage unit, and 30 is a media discrimination unit. It is. Others
The same members as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals.

Hereinafter, the recording operation will be described. Image data taken in from the image source 1 before recording is written in the image memory 2.

When a recording command is issued, the system controller 403 sends a signal indicating the number of each heating element of the thermal head 9 and a signal indicating the first color of the ink paper 10 to the image memory 2 and the correction ROM 503.

The medium discrimination unit 30 sends information on the type of the medium used for recording to the correction ROM 503 and the system controller 403. The media discriminating unit 30 reads from a cassette (not shown) holding the ink paper 10
Alternatively, the type of the medium is determined by a determination switch (not shown).

Further, the system controller 403 receives, from the energization data storage unit 703, the energization time data of the first color corresponding to the gradation number for the determined medium, and sends it to the halftone control unit 3. The energization data storage unit 703 stores energization time data corresponding to a plurality of types of media. If only the energization time data for the discrete gradation numbers can be received from the energization data storage unit 703, the system controller 403 calculates the energization time data for the other gradation numbers by interpolation, and After obtaining the energization time data for the key number, send it.

The image memory 2 sends a signal indicating the gradation number of the image data of the first color to the correction ROM 503 in accordance with the number of each heating element of the thermal head 9 which has been sent, and the image data of the first color. To the image data synthesizing unit 6.
In the correction ROM 503, correction data of the first color for the determined medium is transmitted to the image data synthesizing unit 6 in accordance with the transmitted numbers of the heating elements of the thermal head 9 and the gradation numbers of the image data. .

In the image data synthesizing section 6, the transmitted 1
The color image data and the correction data are combined into corrected image data, and then sent to the halftone control unit 3. In the halftone control unit 3, when the corrected image data for one line is prepared,
The energization time data for the determined medium is received from the system controller 403, and the thermal head 9
Then, a strobe signal having a time width corresponding to the energization time is transmitted. The thermal head 9 supplies a current to the heating element for the time width of the transmitted strobe signal, and the heating element generates heat in response thereto.

On the other hand, the recording paper 11
Is wound, and the first color ink paper 10 is laid thereon, and is pressed by the thermal head 9. The amount of heat generated by the heating element changes according to the energization time (that is, the time width of the strobe signal) specified by the halftone control unit 3,
The ink according to the calorific value is transferred from the ink paper 10 to the recording paper 1.
1 and halftone recording is performed. Similarly, printing is performed in the second and subsequent lines and in the second and subsequent colors according to the corrected image data corrected for each heating element.

Next, the correction data in the correction ROM 503 will be described. FIG. 8 is a characteristic diagram illustrating an example of a gamma characteristic of a medium set in the apparatus. In the present embodiment, a case will be described in which the media A and the media B indicated by a solid line have gamma characteristics of two media.

As described with reference to FIG. 2, in order to realize a certain set gamma characteristic, it is necessary to perform recording with different gamma characteristics for each ink color of the ink paper 10. Further, when the type of media is different, the gamma characteristics are different even if the ink color is the same. Therefore, the density change amount with respect to the gradation change amount differs depending on the gradation number, the color of the ink on the ink paper 10, and further depending on the type of the medium.

FIG. 9 is an explanatory diagram showing an example of correction data in a correction ROM 503 for a certain heating element in the thermal head 9. FIG. 9 shows a case where the image data is 8 bits (256 gradations).

In the medium A, PY0-A (PM0-A, PC0-A), PY1 and PY0-A in accordance with the gradation number of the image data for each color (Ye, Mg, Cy) of the ink on the ink paper 10.
-A (PM1-A, PC1-A) ... PYn-A (PMn
-A, PCn-A), ... PY255-A (PM255-
A, PC255-A) are written for each heating element corresponding to the heating element.

Similarly, in the medium B, PY0-B (P
M0-B, PC0-B), PY1-B (PM1-B, P
C1-B) ... PYn-B (PMn-B, PCn-B),
... PY255-B (PM255-B, PC255-B)
Is written in correspondence with the number of heating elements.

The correction data is a difference data between the resistance value data of each heating element of the thermal head 9 measured in advance and the average value, the maximum resistance value, or the minimum resistance value of the resistance values of all the heating elements. Is obtained for each gradation for each medium and each ink color used, based on the gamma characteristics for each ink color of the ink paper 10 in each of a plurality of types of media that can be used in the apparatus.

Next, generation of corrected image data in the image data synthesizing section 6 will be described. As described above, when the recording command is issued, the system controller 403 transmits a signal indicating the number of each heating element of the thermal head 9 and the ink paper 10.
The signal indicating the color of the first color is stored in the image memory 2 and the correction ROM.
Send to 503.

In the image memory 2, the gradation number of the first image data of the first line of the first color is corrected by the correction ROM 50.
3 to the image data synthesizing unit 6. The correction ROM 503 reads the correction data corresponding to the gradation number of the image data sent from the image memory 2 from the correction data area for the first heating element of the first color for the determined medium, and reads out the correction data. Send to 6.

The image data synthesizing unit 6 synthesizes the image data from the image memory 2 and the correction data from the correction ROM 503 to generate corrected image data, and sends the corrected image data to the halftone control unit 3. For example, in FIG. 9, when the gradation number of the Ye image data is 3, the Ye correction data for the medium A is PY3-A. The image data synthesizing unit 6 adds 3 of the image data and PY3-A of the correction data to obtain (3 + P
Y3-A) is taken as corrected image data.

As described above, according to the present embodiment, the image is adjusted in accordance with the gradation of the image data and in accordance with the gamma characteristic of each ink color of the ink paper 10 for the determined medium. Since the data can be corrected and the optimum corrected image data can be set and recorded for each heating element of the thermal head 9, the recording density becomes uneven due to the variation in the resistance value of each heating element of the thermal head 9. Sex (unevenness) can be corrected.

FIG. 10 is a block diagram showing a thermal transfer recording apparatus according to a fourth embodiment of the present invention, in which 404 is a system controller, 504 is a correction ROM, 704 is an energization data storage unit, and 40 is a correction RAM ( Random access memory). In addition, the same members as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals.

Hereinafter, the recording operation will be described. Image data taken in from the image source 1 before recording is written in the image memory 2.

When a recording command is issued, the system controller 404 sends a signal indicating the number of each heating element of the thermal head 9 and a signal indicating the first color of the ink paper 10 to the image memory 2 and the correction RAM 40.

The system controller 404 receives the energization time data of the first color corresponding to the gradation number from the energization data storage unit 704 and sends it to the halftone control unit 3. If only the energization time data for the discrete gray scale numbers can be received from the energization data storage unit 704, the system controller 404 calculates the energization time data for the other gray scale numbers by interpolation, and After obtaining the energization time data for the key number, send it.

Further, the system controller 404
The representative correction data at the representative gradation number is read from the correction ROM 504, the correction data for all the gradations is calculated by interpolation, and the calculated correction data is written to the correction RAM 40.

The image memory 2 sends a signal indicating the tone number of the image data of the first color to the correction RAM 40 in accordance with the number of each heating element of the thermal head 9 sent thereto.
The first color image data is sent to the image data synthesizing unit 6. Further, in the correction RAM 40, the number of each heating element of the thermal head 9 and the gradation number of the image data sent thereto are
The first color correction data is sent to the image data synthesizing unit 6.

In the image data synthesizing section 6, the transmitted 1
The color image data and the correction data are combined into corrected image data, and then sent to the halftone control unit 3. In the halftone control unit 3, when the corrected image data for one line is prepared,
The energization time data sent from the system controller 404 is received, and a strobe signal having a time width corresponding to the energization time is sent to the thermal head 9. The thermal head 9
A current flows through the heating element for the time width of the transmitted strobe signal, and the heating element generates heat in response to the current.

On the other hand, the recording paper 11
Is wound, and the first color ink paper 10 is laid thereon, and is pressed by the thermal head 9. The amount of heat generated by the heating element changes according to the energization time (that is, the time width of the strobe signal) specified by the halftone control unit 3,
The ink according to the calorific value is transferred from the ink paper 10 to the recording paper 1.
1 and halftone recording is performed. Similarly, printing is performed in the second and subsequent lines and in the second and subsequent colors according to the corrected image data corrected for each heating element.

Next, the calculation of the correction data will be described. FIG. 11 is an explanatory diagram showing an example of representative correction data in a correction ROM 504 for a certain heating element in the thermal head 9.

In FIG. 9, 8 bits (2
56, and 0, 31, 63, 95, 1
27 shows representative correction data at nine representative gradation numbers of 27, 159, 191, 223, and 255.

For each ink color of the ink paper 10 (Ye, M
g, Cy) according to the representative gradation number, PY-0 (PM-
0, PC-0), PY-31 (PM-31, PC-3)
1) PY-223 (PM-223, PC-223),
Representative correction data PY-255 (PM-255, PC-255) is written corresponding to the heating element.

The representative correction data is a difference between the previously measured resistance value data for each heating element of the thermal head 9 and the average value, the maximum resistance value, or the minimum resistance value of the resistance values of all the heating elements. The data is obtained for a representative gradation preset for each ink color based on the gamma characteristic of each ink color of the ink paper 10.

FIG. 12 is an explanatory diagram showing representative correction data for a representative gradation in Ye for a certain heating element in the thermal head 9. Representative correction data is written in the correction ROM 504 by the number of heating elements of the thermal head 9, and as described above, a signal indicating the number of each heating element is received from the system controller 404, and the corresponding representative correction data is selected. . Upon receiving the representative correction data for each heating element, the system controller 404 calculates the correction data at the gradation between the adjacent representative correction data by interpolation calculation. When this interpolation operation is performed for all gradations and correction data for all gradations is calculated, the system controller 404 writes the calculated correction data to the correction RAM 40.

For example, in FIG. 12, when the correction data at 40 gradations of Ye is obtained, the representative correction data PY-31 and PY-63 at 31 gradations and 63 gradations, which are the representative gradations, are obtained. ((PY-63)-(PY-31)) / 32 × (40-
31) + (PY−31) is calculated and converted to an integer to be the correction data for Ye at 40 gradations. The correction data written in the correction RAM 40 holds the data until the power of the apparatus is turned off. As described above, correction data in all gradations is calculated from the representative correction data for each heating element of the thermal head 9.

Next, generation of corrected image data in the image data synthesizing section 6 will be described. As described above, when the recording command is issued, the system controller 404 sends a signal corresponding to the number of each heating element of the thermal head 9 and the ink paper 1.
The signal of the first color of 0 is stored in the image memory 2 and the correction ROM 5.
Send to 03.

In the image memory 2, the gradation number of the first image data of the first line of the first color is corrected by the correction RAM 40.
Then, the image data is sent to the image data synthesizing unit 6. The correction RAM 40 reads out the correction data corresponding to the gradation number of the image data sent from the image memory 2 from the correction data area for the first heating element of the first color, and sends it to the image data synthesizing unit 6. In the image data synthesizing section 6, the image data from the image memory 2 and the correction RAM 40
Is combined with the correction data from the image data to generate corrected image data, which is sent to the halftone control unit 3.

As described above, according to this embodiment, the ink paper 10 is adjusted in accordance with the gradation of the image data.
The image data can be corrected in accordance with the gamma characteristic of each ink color, and the optimum corrected image data can be set and recorded for each heating element of the thermal head 9, so that each heating element of the thermal head 9 can be recorded. The non-uniformity (unevenness) of the recording density due to the variation in the resistance value can be corrected. Further, since the correction data for all the gradations is calculated from the representative correction data for the representative gradations, the necessary amount of correction data can be reduced.

FIG. 13 is a block diagram showing a thermal transfer recording apparatus according to a fifth embodiment of the present invention, wherein 405 is a system controller, 705 is an energization data storage, and 50
Denotes a resistance value measuring unit, and 60 denotes a correction RAM. In addition, the same members as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals.

Hereinafter, the recording operation will be described. Image data taken in from the image source 1 before recording is written in the image memory 2.

When the recording command is issued, the system controller 405 outputs a command to the resistance measuring section 50 to measure the resistance of each heating element of the thermal head 9. The resistance value measuring section 50 measures the resistance value of each heating element of the thermal head 9 and transmits the resistance value data to the system controller 405.
To enter. The system controller 405 temporarily stores the input resistance value data in a memory unit (not shown) provided therein. When the measurement of the resistance values for all the heating elements is completed, the system controller 405 calculates correction data from the basic gamma characteristics set in the apparatus and resistance value data for each heating element, and writes the correction data to the correction RAM 60.

Next, the system controller 405 sends a signal indicating the number of each heating element of the thermal head 9 and the ink paper 10
The signal indicating the first color is stored in the image memory 2 and the correction RAM.
Send to 60.

Further, the system controller 405 receives the energization time data of the first color corresponding to the gradation number from the energization data storage unit 705 and sends it to the halftone control unit 3. If only the energization time data for the discrete gradation numbers can be received from the energization data storage unit 705, the system controller 405 calculates the energization time data for the other gradation numbers by interpolation, and After obtaining the energization time data for the key number, send it.

The image memory 2 sends a signal indicating the gradation number of the image data of the first color to the correction RAM 60 in accordance with the number of each heating element of the thermal head 9 sent thereto.
The first color image data is sent to the image data synthesizing unit 6. Further, in the correction RAM 60, the number of each heating element of the thermal head 9 and the gradation number of the image data sent thereto are
The first color correction data is sent to the image data synthesizing unit 6.

In the image data synthesizing section 6, the transmitted 1
The color image data and the correction data are combined into corrected image data, and then sent to the halftone control unit 3. In the halftone control unit 3, when the corrected image data for one line is prepared,
The energization time data sent from the system controller 404 is received, and a strobe signal having a time width corresponding to the energization time is sent to the thermal head 9. The thermal head 9
A current flows through the heating element for the time width of the transmitted strobe signal, and the heating element generates heat in response to the current.

On the other hand, the recording paper 11
Is wound, and the first color ink paper 10 is laid thereon, and is pressed by the thermal head 9. The amount of heat generated by the heating element changes according to the energization time (that is, the time width of the strobe signal) specified by the halftone control unit 3,
The ink according to the calorific value is transferred from the ink paper 10 to the recording paper 1.
1 and halftone recording is performed. Similarly, printing is performed in the second and subsequent lines and in the second and subsequent colors according to the corrected image data corrected for each heating element.

Next, measurement of the resistance value of each heating element of the thermal head 9 and calculation of correction data from the resistance value data will be described. First, as described above, when a recording command is issued,
The system controller 405 provides the resistance value measurement unit 50 with:
A command to measure the resistance value of each heating element of the thermal head 9 is output, and the resistance measuring unit 50 starts measuring the heating element of the thermal head 9 one element at a time.

In the resistance value measuring section 50, a reference resistor (not shown) having a resistance value that is sufficiently negligible compared to the resistance value of each heating element of the thermal head 9 is connected to a common terminal of the heating element.
The other end is connected to a power supply (not shown). Since each heating element is energized one element at a time, during energization, a current flows through the reference resistance and one element of the selected heating element, causing a voltage drop in the reference resistance. This is amplified and detected by a voltage detection unit (not shown),
The signal is converted into a digital signal of several bits (for example, 8 bits) by an analog / digital converter (not shown) and output to the system controller 405.

The system controller 405 temporarily stores the resistance value data of each heating element of the thermal head 9 in an internal memory unit (not shown), calculates the average resistance value data from the resistance value data of all the heating elements, Difference data is calculated from the resistance value data and the average resistance value data of each heating element. In this embodiment, the difference data is obtained from the average resistance value, but may be the difference data from the maximum resistance value or the minimum resistance value.

Based on the calculated difference data, the basic gamma characteristic set in the apparatus, and the type of medium to be used, correction data for each gradation is determined for each heating element.
Write to. The correction data written in the correction RAM 60 is held until the power of the apparatus is turned off.

As described above, according to this embodiment, the resistance value of the heating element of the thermal head 9 is measured before recording.
Since the correction data is set for the resistance value data for each heating element in accordance with the gradation of the image data and in accordance with the gamma characteristic of each ink color of the ink paper 10, the image data is corrected. The recording is performed with the optimum corrected image data for each heating element, and the non-uniformity (unevenness) of the recording density due to the variation in the resistance value of the heating element of the thermal head 9 can be corrected. Also, by combining with a display means (not shown), when data other than a certain set value is generated, it is possible to display as an abnormality of the thermal head 9,
Useless records are avoided.

In this embodiment, the correction data is obtained by measuring the resistance value of each heating element in the thermal head 9. For example, in FIG. 1, a uniform image with a certain fixed gradation is recorded in advance. Then, the density of each heating element may be measured, correction data for each heating element may be obtained from the resistance value data and the density data, and the correction data may be written in the correction ROM 501.

[0100]

As described above, according to the present invention, the following effects can be obtained. The correction data set in advance based on the resistance value of each heating element of the thermal head and the basic gamma characteristic set in the apparatus is combined with the image data to obtain optimal correction image data for each heating element. Since recording is performed based thereon, the non-uniformity (unevenness) of the recording density due to the variation in the resistance value of each heating element is corrected, and a uniform and good recording result is obtained regardless of the density.

Even when there are a plurality of basic gamma characteristics or a plurality of media, the optimum correction data is set in advance for each of the set basic gamma characteristics or the determined media based on the resistance value. With respect to the set basic gamma characteristic or the determined medium, a uniform and good recording result is always obtained regardless of the density.

Further, by measuring the resistance value of each heating element of the thermal head before recording, even when the resistance value of the heating element changes, optimal correction data is set. The non-uniformity (unevenness) of the recording density due to the variation in the values can be corrected.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a thermal transfer recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram illustrating an example of a gamma characteristic of each ink color of the ink paper 10 according to the first embodiment.

FIG. 3 is an explanatory diagram showing an example of correction data in a correction ROM 501 for a certain heating element in the thermal head 9 according to the first embodiment.

FIG. 4 is a block diagram showing a thermal transfer recording apparatus as a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing an example of a basic gamma characteristic set in the apparatus according to the second embodiment.

FIG. 6 is an explanatory diagram showing an example of correction data in a correction ROM 502 for a certain heating element in the thermal head 9 according to the second embodiment.

FIG. 7 is a block diagram showing a thermal transfer recording apparatus as a third embodiment of the present invention.

FIG. 8 is a characteristic diagram illustrating an example of a gamma characteristic of a medium set in the apparatus according to the third embodiment.

FIG. 9 is an explanatory diagram showing an example of correction data in a correction ROM 503 for a certain heating element in the thermal head 9 according to the third embodiment.

FIG. 10 is a block diagram illustrating a thermal transfer recording apparatus according to a fourth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing an example of representative correction data in a correction ROM 504 for a certain heating element in the thermal head 9 according to the fourth embodiment.

FIG. 12 is an explanatory diagram showing representative correction data on a representative gradation in Ye for a certain heating element in the thermal head 9 in the fourth embodiment.

FIG. 13 is a block diagram showing a thermal transfer recording apparatus according to a fifth embodiment of the present invention.

[Explanation of symbols]

3 ... half tone control unit, 401 ... system controller, 5
01: correction ROM, 6: image data synthesizing unit, 9: thermal head, 20: gamma characteristic selecting unit, 30: media discriminating unit, 40: correction RAM, 50: resistance value measuring unit.

──────────────────────────────────────────────────の Continuation of the front page (72) Inventor Osamu Hattori 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Within Hitachi Media Media Research Laboratory, Inc. (56) References JP-A-5-77468 (JP, A) JP-A-63-209954 (JP, A) JP-A-1-310971 (JP, A) JP-A-2-292060 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2 / 35 B41J 2/36

Claims (5)

(57) [Claims] 1. A heating head having a plurality of heating elements is brought into contact with an ink sheet superposed on a recording paper, and the heating elements of the heating head are heated by energization according to image data, and the heating is performed according to an energization time. A thermal transfer recording apparatus configured to perform gradation recording on the recording paper by changing an amount of heat applied from the body to the ink paper, comprising: a correction data storage unit; and an image data combining unit. The storage means is configured to measure the resistance value of the heating element of the thermal head for each element of the heating element based on the resistance value data obtained by measuring the resistance of the heating element one element at a time and the basic gradation versus density characteristics. Correction data set in advance corresponding to the tone, the image data synthesizing unit stores the image data, and the correction data storage unit from the correction data storage unit corresponding to the gradation of the image data for each heating element. And synthesizing the read correction data and outputting the corrected data as corrected image data, and, instead of energizing according to the image data, causing the heating element of the thermal head to generate heat by energizing according to the corrected image data. Wherein the unevenness in the recording density due to the variation in the resistance value of the heating element is corrected. 2. A heating head having a plurality of heating elements is brought into contact with ink paper superimposed on recording paper, and the heating elements of the heating head are heated by energization according to image data, and the heating is performed according to the energization time. In a thermal transfer recording apparatus configured to perform gradation recording on the recording paper by changing the amount of heat applied from the body to the ink paper, a correction data storage unit, a characteristic selection unit, and an image data combining unit are provided. The correction data storage means, based on resistance value data obtained by measuring the resistance value of the heating element of the thermal head one element at a time, and a plurality of basic gradation versus density characteristics, For each of the basic tone versus density characteristics, correction data set in advance corresponding to each tone is stored for each element of the heating element, and the characteristic selecting means includes a plurality of the basic tone versus density characteristics. From inside A desired basic gradation versus density characteristic is selected and set, and the image data synthesizing unit is configured to correspond to the image data and the gradation of the image data for each heating element from the correction data storage unit. The read and set correction data for the basic tone versus density characteristic are synthesized,
Outputting as corrected image data, instead of energizing according to the image data, causing the heating element of the thermal head to generate heat by energizing according to the corrected image data, thereby recording due to variation in the resistance value of the heating element. A thermal transfer recording apparatus for correcting uneven density. 3. A heat-sensitive head having a plurality of heat-generating elements is brought into contact with ink paper superimposed on recording paper, and heat-generates the heat-sensitive elements of the heat-sensitive head by energization according to image data. A thermal transfer recording apparatus configured to perform gradation recording on the recording paper by changing the amount of heat applied from the body to the ink paper, comprising: a correction data storage unit, a determination unit, and an image data combining unit. The correction data storage means includes a resistance value data obtained by measuring a resistance value of the heating element of the thermal head one element at a time, and a gradation value for each of a plurality of combinations of recording paper and ink paper. And a correction data set in advance for each combination of recording paper and ink paper corresponding to each gradation for each heating element based on the density characteristic. A combination of the recording paper and the ink paper to be used is determined from a plurality of the combinations of the paper and the ink paper. The image data synthesizing unit is configured to store the one heating element from the image data and the correction data storage unit. And the correction data for the determined combination read out in correspondence with the gradation of the image data for each combination and output as corrected image data, and instead of energizing according to the image data, A thermal transfer recording apparatus that corrects recording density unevenness due to variation in resistance value of the heating element by causing the heating element of the thermal head to generate heat by energization according to the corrected image data. 4. The thermal transfer recording apparatus according to claim 1, further comprising a control unit and a storage unit, wherein the correction data storage unit corresponds to each gradation for each heating element. Then, in place of the preset correction data, representative correction data set in advance corresponding to each representative gradation is stored for each of the heating elements, and the control unit stores the representative correction data from the correction data storage unit. The representative correction data is read out, the correction data corresponding to each gradation is calculated by an interpolation operation, the storage unit stores the calculated correction data, and the image data combining unit stores the image data and the correction data. Instead of the data storage means, the correction data read from the storage means for each element of the heating element corresponding to the gradation of the image data is synthesized and output as the corrected image data. Thermal transfer recording apparatus which is characterized in that. 5. A heating head having a plurality of heating elements is brought into contact with ink paper superimposed on recording paper, and the heating elements of the heating head are heated by energization according to image data, and the heating is performed in accordance with an energization time. In a thermal transfer recording apparatus configured to perform gradation recording on the recording paper by changing the amount of heat applied from the body to the ink paper, a resistance value measuring unit, a control unit, a storage unit, and an image data combining unit The resistance value measuring means measures the resistance value of the heating element of the thermal head one element at a time, and obtains resistance value data, and the control means obtains the obtained resistance value data and Calculating correction data corresponding to each gradation for each heating element based on the basic gradation vs. density characteristic; and the storage means storing the calculated correction data; Is before The image data is combined with the correction data read from the storage means for each element of the heating element corresponding to the gradation of the image data, and output as corrected image data. A thermal transfer recording apparatus that corrects recording density unevenness due to variation in resistance value of the heating element by causing the heating element of the thermal head to generate heat by energization in accordance with the corrected image data instead of energization. .